1. Field of the Invention
The present invention relates to a circuit arrangement for an amperometric titration for determining the end point, in which the current between a working electrode and a counter electrode is measured as a function of the total volume of the titration agent added in volume units, and in particular to a circuit arrangement in which the working electrode is operated with a constant polarization voltage with respect to a reference electrode and a closed-loop control is provided for holding the polarization voltage prescribed between the working and the reference electrodes constant, whereby a prescribed reference value voltage is compared to the actual value voltage identified between the working and reference electrodes.
2. Description of the Prior Art
A measurement circuit operating according to the above principle is set forth, for example, in the book "Grundlagen der Technischen Elektrochemie" by Heitz/Kreysa, Verlag Chemie Weinheim/New York, 1971, pp. 6-7. In that arrangement, a constant potential with respect to a reference electrode is applied by means of an electronic potentiostat to the working electrode and the current is measured with the assistance of a milliammeter. By way of a closed-loop control, the current is controlled in such a manner that the difference between a prescribed reference value voltage and the potential between the working and reference electrodes becomes a minimum. This known measurement circuit not only does not operate with precision sufficient for a titration, but is also not suitable for the automation of an amperometric titration for determining the end point, since it is not in a position to emit a magnitude proportional to the current.